X-ray emission from SN 2012ca: A Type Ia-CSM supernova explosion in a dense surrounding medium
Abstract
X-ray emission is one of the signposts of circumstellar interaction in supernovae (SNe), but until now, it has been observed only in core-collapse SNe. The level of thermal X-ray emission is a direct measure of the density of the circumstellar medium (CSM), and the absence of X-ray emission from Type Ia SNe has been interpreted as a sign of a very low density CSM. In this paper, we report late-time (500–800 d after discovery) X-ray detections of SN 2012ca in Chandra data. The presence of hydrogen in the initial spectrum led to a classification of Type Ia-CSM, ostensibly making it the first SN Ia detected with X-rays. Our analysis of the X-ray data favours an asymmetric medium, with a high-density component which supplies the X-ray emission. The data suggest a number density >10^8 cm^(−3) in the higher density medium, which is consistent with the large observed Balmer decrement if it arises from collisional excitation. This is high compared to most core-collapse SNe, but it may be consistent with densities suggested for some Type IIn or superluminous SNe. If SN 2012ca is a thermonuclear SN, the large CSM density could imply clumps in the wind, or a dense torus or disc, consistent with the single-degenerate channel. A remote possibility for a core-degenerate channel involves a white dwarf merging with the degenerate core of an asymptotic giant branch star shortly before the explosion, leading to a common envelope around the SN.
Additional Information
© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 August 4. Received 2017 August 3; in original form 2017 February 8. Published: 23 August 2017. VVD's research is supported by National Aeronautics and Space Administration (NASA) Astrophysics Data Analysis program grant NNX14AR63G (PI Dwarkadas) awarded to the University of Chicago. JMS is supported by an National Science Foundation (NSF) Astronomy and Astrophysics Postdoctoral Fellowship under award AST–1302771. ODF was partially supported by Chandra grant GO4–15052X provided by NASA through the Chandra X-ray Observatory centre, operated by Smithsonian Astrophysical Observatory under NASA contract NAS8–03060. AVF has been supported by the Christopher R. Redlich Fund, the TABASGO Foundation, NSF grant AST–1211916, and the Miller Institute for Basic Research in Science (UC Berkeley). His work was conducted in part at the Aspen Center for Physics, which is supported by NSF grant PHY–1607611; he thanks the Center for its hospitality during the neutron stars workshop in June and July 2017. This research has made use of data obtained from the Chandra Data Archive and software provided by the Chandra X-ray Center (CXC) in the application packages CIAO, CHIPS and SHERPA. We would like the thank the anonymous referee for a helpful and thorough reading of this paper.Attached Files
Published - stx2029.pdf
Accepted Version - nihms-1649603.pdf
Submitted - 1708.07181.pdf
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Additional details
- PMCID
- PMC7720428
- Eprint ID
- 83796
- Resolver ID
- CaltechAUTHORS:20171211-104250823
- NNX14AR63G
- NASA
- AST-1302771
- NSF
- GO4-15052X
- NASA
- NAS8-03060
- NASA
- Christopher R. Redlich Fund
- TABASGO Foundation
- AST-1211916
- NSF
- Miller Institute for Basic Research in Science
- PHY-1607611
- NSF
- Created
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2017-12-12Created from EPrint's datestamp field
- Updated
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2022-03-23Created from EPrint's last_modified field